Utility Model Publication S51-41720 (Jikko Syo 51-41720) published in 1976 by the Japan patent office discloses a front wheel supporting structure of a motorcycle using a pair of front forks. The one of the front forks is operated as an oil pressure shock absorber provided with a damping force generating mechanism for absorbing the vibration by the irregularities on the road surface, and a suspension spring for supporting a vehicle body elastically. The other of the front forks is operated as a guide cylinder at the time of elongation and contraction of the front forks.
Utility Model Publication S49-1162 (Jikko Syo 49-1162) published in 1974 by the Japan Patent Office discloses a pair of front forks one of which is served as an oil pressure shock absorber provided with a damping force generating mechanism and the other of which is served as a guide cylinder provided with a suspension spring.
JPH06-109054A published in 1992 by the Japan Patent Office discloses a front fork provided with a damping force generating mechanism for generating a damping force depending on the velocity of vibration and a damping force generating mechanism for generating a damping force depending on the amplitude of vibration.